Question

In the future we… travel by plane. a. don't b. are not going to c. won't

Answer 1

In the future we won't travel by plane
(Но вообще то в разговорной можно и are not going to употреблять

Answer 2

In the future we are not going to travel by plane.

Answer 3

Future Travel by Plane

In the future, we won't travel by plane.

This is based on the use of "won't" in the sentence, which indicates a future action that is not going to happen